solved task

src/main/java/core/basesyntax/ArrayList.java

@@ -1,48 +1,118 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    private static final double GROWTH_FACTOR = 1.5;
+    private static final int CAPACITY = 10;
+    private T[] elements;
+    private int size;
+
+    public ArrayList() {
+        size = 0;
+        elements = (T[]) new Object[CAPACITY];
+    }
+
+    public void resize() {
+        int newCapacity = (int) (elements.length * GROWTH_FACTOR);
+        T[] newArray = (T[]) new Object[newCapacity ];
+
+        System.arraycopy(elements, 0, newArray, 0, size);
+
+        elements = newArray;
+    }
+
+    private void validateIndex(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index " + index);
+        }
+    }
+
     @Override
     public void add(T value) {
-
+        if (size == elements.length) {
+            resize();
+        }
+        elements[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException("Index " + index);
+        }
+
+        if (size == elements.length) {
+            resize();
+        }
+
+        System.arraycopy(elements, index, elements, index + 1, size - index);
 
+        elements[index] = value;
+        size++;
     }
 
     @Override
     public void addAll(List<T> list) {
-
+        for (int i = 0; i < list.size(); i++) {
+            if (size == elements.length) {
+                resize();
+            }
+            elements[size] = list.get(i);
+            size++;
+        }
     }
 
     @Override
     public T get(int index) {
-        return null;
+        validateIndex(index);
+        return elements[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        validateIndex(index);
+        elements[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        validateIndex(index);
+
+        final T removed = elements[index];
+
+        System.arraycopy(elements, index + 1, elements, index, size - index - 1);
+
+        elements[size - 1] = null;
+        size--;
+        return removed;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int i = 0; i < size; i++) {
+            if ((elements[i] == null && element == null)
+                    || (elements[i] != null && elements[i].equals(element))) {
+                final T removed = elements[i];
+
+                System.arraycopy(elements, i + 1, elements, i, size - i - 1);
+
+                elements[size - 1] = null;
+                size--;
+                return removed;
+            }
+        }
+        throw new NoSuchElementException("Element not found: " + element);
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return (size == 0);
     }
 }